Advancements in optical (photonic) components are enabling a convergence of electrical and optical device interconnections. A first generation of converged I/O modules will likely be based on 10 Gb/s 850 nm vertical cavity surface emitting lasers (VCSELs) and III-V photodetectors, but following generations are expected to move to a 1310 nm carrier wavelength division multiplexing (CWDM) configuration to achieve higher data rates, such as 40 Gb/s and 100 Gb/s, at lower cost.
To provide compatibility across generations, converged I/O receivers should ideally be able to efficiently detect both 850 nm and 1310 nm bands. Because it is expected light will be provided via multi-mode fiber for reduced packaging costs, both 850 nm and 1310 nm light will be introduced at the same point. Generally, silicon-based optical solutions are preferable over III-V technologies because silicon offers significant cost saving. However, because silicon absorbs 850 nm light, silicon-based solutions are potentially precluded from certain converged I/O applications.